WORKSHOP ON HISTOLOGY, CYTOLOGY AND EMBRYOLOGY - 2016

Chapter 3. GENERAL EMBRYOLOGY. HUMAN EMBRYOLOGY.

Slide 19. Cross-section of a chick embryo at the stage of primary mesoderm differentiation.

Staining: iron hematoxylin.

Magnification: x80.

Examine the slide under low magnification. The ectoderm (1) forms a continuous layer covering the dorsal surface of the embryo. Centrally, underneath the ectoderm, lies the oval-shaped neural tube (2), with its lumen—the neurocoel (3)—visible as an elongated cleft. Positioned directly beneath the neural tube is the notochord (4), which appears circular in cross-section. The ventral surface of the embryo is lined by the endoderm (5). The gut tube is not yet formed. Situated between the endoderm and ectoderm is the mesoderm (6), which has already undergone primary differentiation. Flanking the neural tube on both sides are the somites (7), appearing as dense cellular aggregates. More laterally, the mesoderm narrows to form the nephrotome (8), or intermediate Cell mass. Further laterally, the nephrotome splits into two layers of the splanchnotome: the parietal layer (9) and the visceral layer (10). Enclosed between them is the primary body cavity, or coelom (11). Occasionally, primary Blood Vessels can be observed beneath the visceral layer, formed by Cells migrating outward from the visceral layer of the splanchnotome. Primitive Blood Cells are visible within the lumen of these vessels.

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Slide 19. Cross-section of a chick embryo at the stage of primary mesoderm differentiation.



Last update: 07/08/2026

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